Mounting structure for thermistor with positive resistance-to-temperature characteristic

Abstract

A thermistor with positive resistance-to-temperature characteristic used in a overcurrent protection circuit has electrodes on mutually opposite main surfaces and is mounted to a substrate having electrically conductive members such that deterioration of its voltage resistance due to heat emission can be controlled. A spacer with smaller thermal conductivity than the substrate and penetrated by a conductor piece with a small cross-sectional area is inserted between solder materials connecting to one of the thermistor electrodes. The other electrode is contacted by an elongated connecting member through its sectional surface transverse to its longitudinal direction such that the cross-sectional area of electrical conduction is reduced.

What is claimed is:  
     
       1. A structure comprising: 
       a substrate;  
       a thermistor mounted to said substrate, having a first main surface and a second main surface, which are facing mutually oppositely facing, a first electrode on said first main surface and a second electrode on said second main surface;  
       a first electrically conductive connecting member and a second electrically connecting member which are each attached to said substrate and contacting a corresponding one of the electrically conductive connective members only over a limited contact area which is significantly smaller than areas of the first and second electrodes, wherein flow of heat from said thermistor to said substrate is constrained, wherein said first main surface faces away from said substrate, said first connecting member comprises a metallic plate having a ridge, said ridge contacting said first electrode, wherein said second main surface faces towards said substrate, said second connecting member having protrusions and contacting said second electrode only through said protrusions, wherein said first connecting member is bridge-shaped with two legs, each of said legs being attached to a conductive land through solder to said substrate.